The present invention relates to a layered winding, advantageously a high voltage layered winding, for a transformer with striplike conductor insulated with at least one strip of insulation folded about the conductor. Such insulation can be applied in the course of the layered winding of the conductor with a strip of insulation that corresponds to about three times the width of the conductor, so that the insulation strip can be folded double about the conductor.
A process for insulation of striplike conductors for choke or transformer coins of the described type is known, for example, from German Offenlegungsschrift No. 15 63 458. It is a disadvantage in this known process that adhesive is supplied for fastening of the conductor insulation and at the same time of the individual paper layers respectively upstream of the folding devices. This admittedly leads to an adequate bonding of the paper insulation that is folded about the conductor, but fastening of the winding layers is only guaranteed if the adhesive material is applied to the insulation paper in excess so that part of the adhesive will soak through the folding joints and thereby allow bonding of the corresponding winding of the next layer. Such a process is not suitable, to impart the necessary mechanical strength to a layered winding that comprises a plurality of layers, especially a high voltage layered winding. Also exact impregnation is difficult because the bonding places are largely undefined, between the individual layers.
The present invention is concerned with the problem of so improving a transformer winding of the mentioned type, made as a layered winding, advantageously a high voltage layered winding, that the mechanical strength will be adequate even with a large number of layers. Also, impregnation is not to be hampered by measures taken for fastening the individual winding layers. Especially however, the present invention concerns a fully automatic, preferably program-controlled winding technique.
This problem is solved according to the present invention in that the insulation strip in addition to the conductor insulation forms at the same time the insulation of the layers. Along the periphery of a winding layer, at specific distances, punctate bonding places are located only on the outside of the layer insulation, serving for fixation of the next succeeding winding layer. Further, according to the present invention, the length of the winding layers is so shortened from layer to layer that the cross section of the layered winding is trapezoidal at first or at least essentially trapezoidal, while the transition to the free outer end of the layered winding comprises one or more circular arcs with different radii.
It is important for the fully automatic winding process that the conductor insulation forms the layer insulation at the same time. This eliminates the tedious winding in or shooting in of the layer insulation, which has made the manufacture of known layered windings difficult and expensive. It is also favorable that the punctate bonding places disposed on the outside of the conductor insulation yields an outstanding fixation of the individual winding layers, and therewith a compact winding structure. At the same time, the remaining gaps between the bonding places allow adequate impregnation with liquid or gaseous impregnating materials. It is also favorable that because of the arcuate transition from the trapezoid or essentially trapezoid part of the winding to the free outer end of the layered winding, the shielding electrode on a high voltage potential can be made very simply. By the selected winding structure, an excellent layer control is obtained.
There is a further advantage according to the present invention if the individual windings of a layer formed by the striplike conductor together with its insulation border on each other at the front with no spacing between them. The use of striplike conductors with a width that is substantially greater than the thickness makes possible the winding of layer on layer without any space between, without the layer tension thereby becoming excessive, despite the lack of a supplementary layer insulation. Also, the impregnation with liquid or gaseous impregnants requires no frontal separation of the individual windings of a layer. On the other hand, gaps caused in manufacture which amount to fractions of a millimeter, between the individual fronts of the windings are not disturbing and can even promote the process of impregnation.
According to an additional feature of the present invention the layered winding is essentially trapezoidal in cross section but with the free fronts of the layered winding beginning like an e-function and then going over into a linear part to which then the circular terminal arc is connected as shown in FIG. 4a. Also, an immediate transition from a side surface curved like an e-function into the circular terminal arc is possible as depicted in FIG. 4b.
The invention further relates to a process for the production of a transformer winding, advantageously a high voltage layered winding with striplike conductor whose insulation is applied in the course of the layered winding of the conductor using an insulation strip which is folded about the conductor. In particular, the insulation strip may have a width about three times the width of the conductor so that the insulation strip can be folded double about the conductor. This process is characterized in that the folding of the insulation strip about the striplike conductor is undertaken in several stages, that the insulated conductor is guided over a deflector roll in such a way that the conductor part running onto the deflector roll and the conductor part running off the deflector roll describe a sharp angle and that the strip insulation of adjacent layers is bonded at punctate bonding places spaced at predetermined distances. In one preferred process a bonding material is applied to the outside of the winding of a layer shortly before overlaying the new winding of the adjacent layer.
The folding of the insulation strip about the striplike conductor in several stages makes possible the use of a folding device that is comparatively simple to produce. The deflection of the insulated striplike conductor via the deflector roll has the effect that the insulating material firmly encloses the conductor, so that bonding of overlapping parts of the insulation strip can be eliminated.
These and other objects, features and advantages of the present invention will become more apparent from the following description when taken in connection with the accompanying drawings, which show, for purposes of illustration only, several embodiments in accordance with the present invention.